The present invention relates to an articulated vehicle and more particularly to an articulation lock for locking the articulating joint between the two bogies or frames of the articulated vehicle.
It is known to provide articulated vehicles having articulated bearings which pivotally connect a front bogie with a rear bogie of the vehicle. These vehicles are usually steered by a pair of hydraulic actuators mounted on opposite sides of the articulation joint centerline. One hydraulic actuator is extended while the other is retracted to pivot the vehicle to the left or right about the articulation joint. The hydraulic actuators control the pivoting as long as there is pressurized fluid in the hydraulic system.
There are numerous occasions when it is necessary to lock the articulating joint in a fixed position such as for transportation or maintenance. When the vehicle is being transported, and the power is turned off, there is a need for an articulating joint lock so that the front and rear bogies do not shift out of alignment on the transporter. Another situation where a lock is needed occurs when a person is performing maintenance on the vehicle, and it is desirable that the vehicle be articulated and locked to a maximum position either right or left.
The front and rear bogies are large, and when the power is off the vehicle may articulate when parked, especially on an incline. Thus, when the power steering is deactivated, the pivot joint is freely pivotable, and it is difficult to hold the immense frames in a fixed position if the joint is not locked.
The prior art articulation locks have not been satisfactory because the operator has had to leave the operator's cab to lock the articulation joint. One prior art approach requires that the operator lock the joint by using a lock bar between the front and rear frames. This is a cumbersome arrangement because the frames have to be aligned and the lock bar may be lost or not readily available. Thus, the vehicle may be left unlocked because the prior art devices are typically inconvenient and time-consuming to use.
There is a need for an articulation lock that can be engaged when the machine is running and the operator is still in the operator's cab. For maintenance purposes and other reasons, it is desirable to lock the vehicle in a straight-ahead position, a maximum left position, or a maximum right position. This can be done most easily while the machine is still running and the operator has power to articulate the frames to the desired position. Convenience is a primary reason for locking the pivot joint while the machine is running and the operator is in the cab. It is desirable that the operator be able to lock the vehicle joint in the desired position before he turns the power off and leaves the cab. Otherwise, he may not trouble himself in locking the machine, and the frame then becomes subject to the undesired movement about the pivot joint and disadvantages described hereinbefore.
These disadvantages in present articulation lock constructions have resulted in the articulation lock in the present invention which permits the operator of an articulated machine to lock the vehicle while it is running without leaving the operator's compartment.